A fuel cell using a polymer electrolyte is used for portable power supply, power supply for electric cars, home cogeneration systems and so on. A fuel cell using a polymer electrolyte generates electric power and heat at the same time by causing a fuel gas containing hydrogen and an oxidizer gas containing air such as oxygen, to electrochemically react with each other.
A fuel cell using a polymer electrolyte generally includes a polymer electrolyte membrane which selectively transports hydrogen ions, and a pair of electrodes which sandwich the polymer electrolyte membrane. The electrodes include a catalyst layer which is primarily composed of carbon particles supporting a platinum group metal catalyst, and a gas diffusion layer which is formed outside the catalyst layer and which is both breathable and electronically conductive.
To prevent the supplied fuel gas and oxidizer gas from leaking outside or to prevent the two gasses from mixing with each other, a gas sealant and gaskets are provided around the electrodes so as to sandwich the polymer electrolyte. The sealant and gaskets are assembled in advance integral with the electrodes and the polymer electrolyte membrane. This assembly will be referred to as an “MEA (Membrane Electrode Assembly).”
Conductive separators are placed on both planes of an MEA to mechanically hold the MEA and electrically connect the MEA with neighboring MEAs in series. A channel is formed on the face where the separator and the MEA contact, to supply a reactive gas to electrode surface and carry away the water produced and surplus gas. The channel may be provided apart from the separators, but, usually, a groove is provided on the surfaces of the separators as a channel. Moreover, generally, a plurality of battery cells, in which each cell is made up of an MEA and a pair of separators, are stacked together and the MEAs are electrically connected in series, to increase voltage and make a cell stack of practical use.
When a battery cell is made by combining an MEA and a pair of separators, if displacement occurs between the electrode surface of an MEA and the channel surface of a separator, the effective reaction area is reduced and a desired voltage cannot be obtained. Furthermore, when a plurality of battery cells are stacked together, an MEA and a pair of separators making up a battery cell are preferably integrated so as to prevent displacement between MEAs and separators.
In order to regulate the positions of the MEA and a pair of separators of a battery cell and integrate these components, a method has been proposed of inserting positioning pins in through-holes provided in the MEA and the pair of separators in places other than the reaction surfaces and fastening the positioning pins with retaining rings to prevent the pins from falling (see Patent Document 1).
A proposal of integrating an MEA and a pair of separators by clipping perimeter edges of the MEA and the separators using a clip-like part (see Patent Document 2) or a proposal of fitting a pair of separators, between which an MEA is sandwiched, is fitted with each other via resin suction cups (see Patent Document 3), has been made.    Patent Document 1: Japanese Patent Application Laid-Open No. 2000-012067    Patent Document 2: Japanese Patent Application Laid-Open No. 2004-241208    Patent Document 3: Japanese Patent Application Laid-Open No. 2005-142000